The main objective of this project is to provide a research resource (the Chemobyl Tissue Bank: CTB) for both ongoing and future studies of the health consequences of the Chemobyl accident. It seeks to maximize the amount of information obtained from small pieces of tumor by providing multiple aliquots of RNA and DNA extracted from well-documented pathological specimens to a number of researchers worldwide and to conserve this valuable material for future generations of scientists. It exists to promote collaborative, rather than competitive, research on a limited biological resource. The CTB ensures that the best possible diagnostic service is provided to patients and that appropriate ethical consent is obtained for each biological sample, that specimens are properly documented and sampled and that biological materials are available for appropriate research studies. A diagnosis for each sample, agreed by internationally recognized pathologists, is made available to research groups carrying out molecular biological, therapeutic, epidemiological and other studies. The CTB provides an archive of research data generated from research studies carried out using the resource material. This data may have direct relevance to both prognosis and assessment of risk from exposure to radioactive fallout from a nuclear accident. The CTB allows multiple researchers access to the same material, permitting comparison of different techniques for the same molecular marker and analysis of multiple molecular markers. It provides the opportunity for additional markers (as yet unknown) to be studied in the future. A number of similar projects to amass biological archives from specific patient groups exist. However, few of these projects seek, from their outset, to collate research data produced from the samples collected. This archive is different in that it deals with a relatively rare tumor whose a etiology is known (exposure to radio iodine in fallout), therefore enabling study of the interaction of environment and physiology, it is highly likely that many of the mechanisms involved in thyroid carcinogenesis are common to other cancers. The research supported by this resource may therefore have other benefits to the treatment of cancers in other tissues.